Electrophotographic photoreceptor, production method thereof, and electrophotographic apparatus

Abstract

An electrophotographic photoreceptor includes an electroconductive substrate; and a photosensitive layer that is formed on the electroconductive substrate and that contains an inorganic oxide and a lubricant resin which contains a polycarbonate resin having a siloxane structure therein or a polyarylate resin having a siloxane structure therein. When light having a wavelength of 780 nm is irradiated onto a slurry containing 20% by mass of the inorganic oxide in a predetermined solvent to provide an inorganic oxide slurry, the inorganic oxide slurry has a light transmittance that is 80% or more. The photosensitive layer may be a negatively-charged laminate-type photosensitive layer, a monolayer type photosensitive layer, or a positively-charged laminate-type photosensitive layer. The electrophotographic photoreceptor is less worn upon long-term use, allows no filming, and can realize stable images. A method for producing the electrophotographic photoreceptor and an electrophotographic apparatus including the electrophotographic photoreceptor are disclosed.

Description

CROSS-REFERENCE TO RELATED APPLICATION(S)[0001]This non-provisional application for a U.S. patent claims the benefit of priority of JP 2019-050275 filed Mar. 18, 2019, the entire content of which is hereby incorporated by reference.BACKGROUND OF THE INVENTION1. Field of the Invention[0002]The present invention relates to an electrophotographic photoreceptor (hereinafter, also referred to as a “photoreceptor”), a production method thereof, and an electrophotographic apparatus. Specifically, the present invention relates to an electrophotographic photoreceptor which is mainly composed of a photosensitive layer including an electroconductive substrate and an organic material, and is used for an electrophotographic printer, a copying machine, a fax machine, etc., a production method thereof, and an electrophotographic apparatus.2. Background of the Related Art[0003]An electrophotographic photoreceptor has a basic structure in which a photosensitive layer having a photoconductive functio...

AI Technical Summary

Benefits of technology

This patent describes a photoreceptor with improved resistance to wear and image quality. The inventors found that by using an inorganic oxide in the photosensitive layer, the mechanical strength of the layer is increased, resulting in a longer lifespan and stable image quality. However, the inorganic oxide alone can cause high viscosity and aggregability when dispersed in a solvent. To address this, the inventors discovered that by using a high-concentration inorganic oxide dispersed in a low-viscosity solvent, with low friction between the cleaning blade and the photoreceptor surface, filming (unstable image quality) can be reduced. This combination of inorganic oxide and lubricant resin provides both wear resistance and filming resistance, and has not been previously known in the field of photoreceptors.

Problems solved by technology

Furthermore, when paper powder and external additives remain on the blade, scratches are made on the surface of an organic photoreceptor and can shorten the life of the photoreceptor.

Therefore, the photoreceptor is increasingly worn, resulting in potential variation, sensitivity variation, and image abnormality, and, in the case of a color machine, resulting in failures in color balance and reproducibility.

Further, if a reverse-polarity toner, which may be mixed in an extremely small amount, is present, there is a problem that such toner cannot be sufficiently removed from the photoreceptor surface, and the charging device is contaminated.

Further, ozone, nitrogen oxides and the like generated upon charging of a photoreceptor may contaminate the photoreceptor surface.

This causes a problem of image deletion due to contaminants themselves, and a problem such that adhered substances lower the lubricity of the photoreceptor surface and facilitate adhesion of paper powder and toners, which causes blade noise, peeling, and formation of scratches on the surface.

However, uniform dispersion of a filler is difficult by such a method that involves dispersing a filler in a film.

Further, the presence of filler aggregates, decreased film transmittance and exposure light scattered by a filler result in non-uniform charge transport and charge generation, and thus image characteristics may deteriorate.

Further, there is a method that involves adding a dispersion material in order to improve filler dispersibility, but in this case, the dispersion material itself adversely affects photoreceptor characteristics, making it difficult to sufficiently achieve both the photoreceptor characteristics and filler dispersibility.

Furthermore, while the addition of a filler improves wear resistance, filming takes place easily on the photoreceptor surface, and handling of image failures is also not taken into consideration.

Further, Patent Documents 3, 4, 5 and 6 propose that a photosensitive layer contains filler particles in order to improve wear resistance, however, photoreceptor characteristics affected by particle aggregation upon preparation of a photosensitive layer coating solution, a production method of particles, effects on impurity control and surface treatment are not sufficiently verified.

Further, Patent Document 7 proposes that in order to obtain a photoreceptor causing less wears upon long-term use and being capable of realizing stable images, a photosensitive layer is formed using an inorganic oxide satisfying predetermined conditions, however, a problem of filming on the photoreceptor surface is not examined.

However, these methods that involve forming a surface protective layer is problematic in that film formation on a charge transport layer is difficult, and achieving both charge transport performance and charge retention function sufficiently is difficult.

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